Cloud nine cabs

Not so long ago, “tractor comfort” was a contradiction in terms. Back sore? Get an old cushion and tie it to the metal pan seat. Hot? Then mount a big umbrella to the fender and block the sun. On most tractors, anything to do with human comfort was an afterthought. Design engineers focused on the machine. The engine. The transmission. Pulling power. And, oh yeah, better bolt a seat to this thing so someone can drive it.

Those days are gone. In an industrywide trend that started somewhere in the early 1990s, tractor cabs have approached the comfort and luxury of top-of-the-line automobiles. In a recent presentation to the Agricultural Safety and Health Network, Lloyd Redding with Case New Holland and chairman of the Equipment Manufacturer's Institute Ag Safety Committee noted that tractor seats use the latest suspension technology, visual obstructions have been reduced, and getting into a cab is “close to walking up the steps in a house.” Welcome to the golden age of comfortable cabs.

Soft-touch Gleaner

Tom Draper, general marketing manager for Gleaner combines, likes to talk about the importance of cab design in his company's next generation of machines. “We've all heard about how site-specific farming is leading us toward an era of driverless farm machines, but I don't think that's where the industry is going,” he says. “Rather than a revolution, we'll see an evolution, with more technologies that make the operator work more efficiently with the machine. We're going to see that some of the most important advances in combines, tractors and other machines are going to come in the form of cabs that are quieter, gentler and easier to operate.”

The idea, Draper says, is to make the operation of the machine simpler even as more functions and sophisticated electronics are added. Innovations such as controls with a “memory,” which allow headers to return to the same height at the end of a headland turn, relieve the driver of some of the burden of operation.

Cat starts from scratch

Gary Uken serves as technical leader on Caterpillar's new MT700 farm tractor. “We had the luxury of looking at what worked and what needed improvement on previous tractor models,” Uken says. “Then, for the MT700, we started with a clean sheet of paper.”

After Uken's team of engineers and designers “roughed-in” the new tractor's surface geometry with a high-powered Computer Aided Design program, they turned to the simple and time-proven methods product designers have used for centuries: They headed to the wood shop and sculpted a model.

It wasn't long before farmers and dealers were sitting in a full-sized prototype cab, reaching for levers and moving around. Mounted atop a full-scale prototype machine, the cab was analyzed and reanalyzed by operators of all shapes and sizes. Filling out a score sheet, the testers gave their impressions on comfort, ease of use, fit and finish.

“We made more refinements from there,” Uken says. “And we soon realized that one of the keys to comfort and efficiency over a long work day was the armrest and its controls. Additionally, it became evident that tractor buyers want a certain ‘feel’ of quality in the cab. To be satisfied, today's tractor driver expects the same fit and finish you'd see in a nice pickup truck. So on the MT700 we've made it so that cab components such as plastic panels look and feel good. Wrap your knuckles on the dash and it sounds solid. Close the door and you get a satisfying thunk.”

The MT700 features improvements such as Surround-Flow ventilation, one-touch control management, improved seat suspension, “marshmallow” springs to isolate the driver from hard bar vibration, and butyl rubber mounts between the tractor and the cab.

“These features all create measurable improvements in the cab,” Uken says. “Yet things like cab space and quality components create an equally important, if less measurable, perception of comfort. So we're paying more attention to lots of little things. The details can add up to an overall perception of comfort and quality.”

Virtually there

Wooden models can go only so far in telling cab designers how a total cab environment will actually perform. In the end, a real cab has to be mounted on a tractor and tested in the field. Then any surprise problems with the cab, such as poor airflow to the driver, may require an expensive and possibly rushed rebuild. Or designers must face the disappointing prospect that they'll have to wait until the next model year to introduce a better cab.

Seeking to limit such costly trial-and-error design, engineers have worked with computer experts, analyzing reams of cab data to try and conjure up what cab airflow might look like. Those efforts, though somewhat successful, were often stymied by the limitations of trying to use slices of two-dimensional data to represent a three-dimensional cab environment.

Now thanks to more powerful computers and innovative program design, a new era of virtual prototyping not only lets designers look at the data, it lets them get inside a virtual cab and move around as they would in an actual tractor or combine cab. One of today's most advanced virtual reality (VR) facilities is called the C6, located on the Iowa State campus in Ames. Used by clients that include the U.S. Air Force, Boeing and John Deere, the C6 creates a 360° immersion experience with six stereoscopic screens, a three-dimensional sound system and various wireless technologies. Using this device, a user is able to navigate through and manipulate virtual worlds, even a virtual farm field as viewed from a tractor cab.

Jerry Duncan, senior staff engineer with John Deere's product technology department, explains how the computer-generated environment can show something as complex as in-cab airflow. “A designer or engineer wearing stereoscopic 3-D glasses can now enter a virtual reality room where the walls, ceiling and floor are rear-projection screens,” Duncan says. “The visual effect is far more lifelike than you'd expect, like a 3-D Omnitheater, only much better. You can actually move your head around and see the cab from different angles. Input some data to show a graphic representation of airflow, and the person inside the VR room can look around and see the fluid dynamics in action, including where the eddies and dead air spots will ultimately show up in a real cab. If airflow isn't getting to the back of the operator's neck, for example, you'll see it. The VR technology simply lets us see things that we didn't know were there before.”

Duncan explains that the value of VR is getting “the human in the loop” early in the design stage. “Once you get a cab built, it's difficult to make changes. Everyone who's touched it has a big investment. But with VR we can get input and decisions made before we build anything.”

And, he says, because the C6 can show different types of data in formats that different types of people can understand, everyone from engineers to marketing people to farmers can check out a new cab design and give their input up front.

“Airflow in the cab is just one example of how we can use VR prototyping to make improvements early in the design process,” Duncan says. “In fact, we can now look at VR models for every part of the tractor, from the cab to the complete power train.”

To learn more about C6 and the Iowa State Virtual Reality Applications Center, visit www.vrac.iastate.edu.

Sit and be fit

Thanks to new seats, riding a tractor all day doesn't have to beat you up.

What is comfort? That's the question 10 scientists sought to answer at an ergo-mechanics conference in Amberg, Germany, this past October. The conference, sponsored by seat manufacturer Grammer AG, included presentations on everything from “spinal load stabilization” to “the psychology of sitting.” Psychologist Elke Maria Deubzer summed up the theme of the conference this way: “If you sit well, you will achieve your goals more easily.”

Sitting well

One message of the conference was that sitting in a relaxed position, even with a rounded back, puts considerably less stress on the spine than a rigid upright posture. And an adjustable seat, with adequate support and protection from excessive jarring, helps reach this goal.

Practically every modern seat, from the most basic to the most plush, is built upon the principles of ergo-mechanics, the study of how the human body works and how to keep it comfortable and productive in work environments such as tractor cabs. And while the highest-tech solutions to comfort may receive the most press, the basic seat models, available as standard equipment on most machines, may make the biggest impact on how many farmers will end their day without a backache.

Standard comfort

Seat manufacturing companies such as Grammer AG build the standard equipment seats that go into most major brands of tractors. Michael Bur, vice president of sales and operations at Grammer, says his company is one of approximately six major seat manufacturers that build seats ranging from those with complex suspensions to simple molded seats with no suspension at all. “Everyone likes to talk about their top-of-the-line seat, and we're no exception,” Bur says. “But the fact is that approximately 75% of the seats that go into U.S. tractors and other equipment have no suspension at all. The safety and comfort of those seats is just as important.”

One example of a suspensionless seat is Grammer's S-300 seat built in Hudson, WI. The low-cost seat is used in skid steers. The seat's narrow base is designed to fit within the cab's limited space. Further, Bur says the seat's cushioning foam will soon be a durable and environmentally friendly soy-based material.

Luxury model

At the higher end, Grammer's Universo XM seats are the adjustable air suspension seats installed in some John Deere tractors. Ordered through a John Deere dealer, these sell for about $1000.

“Any seat we make goes through extensive testing for durability and comfort,” Bur says. “We have testing machines to simulate six years of hard use. We can see how each seat will hold up after a farmer gets in and out of it a quarter-million times.” And if the scientists who work with Grammer got their definition of comfort right, the farmer will have held up better too.